Module: PWN::SDR::Decoder::Flex

Defined in:
lib/pwn/sdr/decoder/flex.rb

Overview

Flex Decoder Module for Pagers

Class Method Summary collapse

Class Method Details

.authors ⇒ Object

Author(s)

0day Inc. <[email protected]>



237
238
239
240
241
 
# File 'lib/pwn/sdr/decoder/flex.rb', line 237

public_class_method def self.authors
  "AUTHOR(S):
    0day Inc. <[email protected]>
  "
end

.decode(opts = {}) ⇒ Object

Supported Method Parameters

pocsag_resp = PWN::SDR::Decoder::Flex.decode(

freq_obj: 'required - GQRX socket object returned from #connect method'

)



18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
 
# File 'lib/pwn/sdr/decoder/flex.rb', line 18

public_class_method def self.decode(opts = {})
  freq_obj = opts[:freq_obj]
  gqrx_sock = freq_obj[:gqrx_sock]
  udp_ip    = freq_obj[:udp_ip]    || '127.0.0.1'
  udp_port  = freq_obj[:udp_port]  || 7355

  freq_obj.delete(:gqrx_sock)

  skip_freq_char = "\n"

  puts JSON.pretty_generate(freq_obj)
  puts 'Press [ENTER] to Continue to next frequency...'

  # Spinner setup with dynamic terminal width awareness
   = TTY::Spinner.new(
    '[:spinner] :status',
    format: :arrow_pulse,
    clear: true,
    hide_cursor: true
  )

   = 12
  max_title_length = [TTY::Screen.width - , 50].max

  initial_title = "INFO: Decoding #{self.to_s.split('::').last} on udp://#{udp_ip}:#{udp_port} ..."
  initial_title = initial_title[0...max_title_length] if initial_title.length > max_title_length
  .update(status: initial_title)
  .auto_spin

  skip_freq = false

  # === Replace netcat with PWN::Plugins::Sock.listen ===
  udp_listener = PWN::SDR::GQRX.listen_udp(
    udp_ip: udp_ip,
    udp_port: udp_port
  )

  # Combined processing pipeline: sox → multimon-ng
  decode_cmd = '
    sox -t raw -e signed-integer -b 16 -r 48000 -c 1 - \
        -t raw -e signed-integer -b 16 -r 22050 -c 1 - | \
    multimon-ng -t raw \
      -a FLEX \
      -a FLEX_NEXT \
      -
  '

  mm_stdin, mm_stdout, mm_stderr, mm_wait_thr = Open3.popen3(decode_cmd)

  current_title = 'Waiting for data frames...'

  # Thread: read from UDP listener and feed to sox|multimon pipeline
  receiver_thread = Thread.new do
    begin
      loop do
        data, _sender = udp_listener.recv(4096)
        next unless data.to_s.bytesize.positive?

        mm_stdin.write(data)
        mm_stdin.flush rescue nil
      end
    rescue IOError, Errno::EPIPE, EOFError, Errno::ECONNRESET
      # normal exit path when shutting down
    end
  end

  # Thread: read decoded output from multimon-ng and display it
  decoder_thread = Thread.new do
    # buffer = +''
    buffer = ''

    valid_types = %w[ALN BIN HEX NUM TON TONE UNK]
    loop do
      begin
        chunk = mm_stdout.readpartial(4096)
        # buffer << chunk
        buffer = "#{buffer}#{chunk}"

        while (line = buffer.slice!(/^.*\n/))
          line = line.chomp
          next if line.empty? || !line.start_with?('FLEX')

          decoded_at = Time.now.strftime('%Y-%m-%d %H:%M:%S%z')
          dec_msg = { decoded_at: decoded_at }
          dec_msg[:raw_inspected] = line.inspect

          protocol = line[0..8]
          protocol = 'FLEX' unless protocol == 'FLEX_NEXT'
          dec_msg[:protocol] = protocol

          # ────────────────────────────── Detect format ──────────────────────────────
          # Sometimes Flex is space delimited, sometimes pipe delimited
          # FLEX_NEXT appears to always be pipe delimited

          delimiter = '|'
          space_delim = false
          if line.start_with?('FLEX: ')
            delimiter = ' '
            space_delim = true
          end

          flex_pipe_delim = false
          flex_pipe_delim = true if line.start_with?('FLEX|')

          parts = line.split(delimiter)

          # protocol index already used
          idx_already_used = [0]
          target_parts_idx = 1
          target_parts_idx += 1 if flex_pipe_delim
          target_parts_idx += 2 if space_delim
          dec_msg[:speed] = parts[target_parts_idx] if parts[target_parts_idx]
          idx_already_used.push(target_parts_idx)

          target_parts_idx += 2
          dec_msg[:capcode] = parts[target_parts_idx] if parts[target_parts_idx]
          idx_already_used.push(target_parts_idx)

          target_parts_idx -= 1
          dec_msg[:capcode_loc] = parts[target_parts_idx] if parts[target_parts_idx]
          idx_already_used.push(target_parts_idx)

          while target_parts_idx < parts.size
            if idx_already_used.include?(target_parts_idx)
              target_parts_idx += 1
              next
            end

            key = parts[target_parts_idx]
            key = 'long_sequence_number' if key == 'LS'

            if key && valid_types.include?(key)
              dec_msg[:type] = key

              dec_msg[:type_desc] = case key
                                    when 'ALN'
                                      'Human-readable text'
                                    when 'BIN'
                                      'Binary / data payload (typically 32 bit words)'
                                    when 'HEX'
                                      'Raw hex representation of data'
                                    when 'NUM'
                                      'Numbers only'
                                    when 'TON', 'TONE'
                                      'Just alert tone, no message'
                                    when 'UNK'
                                      'Decoded but type unknown / unsupported format'
                                    end

              target_parts_idx += 1
              payload_parts = parts[target_parts_idx..]
              dec_msg[:type_payload] = payload_parts.join(delimiter)

              break
            else
              target_parts_idx += 1
              dec_msg[key] = parts[target_parts_idx] if parts[target_parts_idx]
            end

            idx_already_used.push(target_parts_idx)
            target_parts_idx += 1
          end

          final_msg = freq_obj.merge(dec_msg)
          puts JSON.pretty_generate(final_msg)
          # TODO: Append dec_msg to a log file in a better way
          flex_log_file = "/tmp/flex_decoder_#{Time.now.strftime('%Y%m%d')}.log"
          File.open(flex_log_file, 'a') do |f|
            f.puts("#{JSON.generate(final_msg)},")
          end
        end
      rescue EOFError, IOError
        break
      end
    end
  end

  loop do
    .update(status: current_title)

    # Non-blocking ENTER check to exit gracefully
    next unless $stdin.wait_readable(0)

    begin
      char = $stdin.read_nonblock(1)
      next unless char == skip_freq_char

      skip_freq = true
      puts "\n[!] ENTER pressed → stopping decoder..."

      break
    rescue IO::WaitReadable, EOFError
      # ignore
    end

    break if skip_freq
  end

  .success('Decoding stopped')
rescue StandardError => e
  .error("Decoding failed: #{e.message}") if defined?()
  raise
ensure
  # Cleanup
  [receiver_thread, decoder_thread].each do |thread|
    thread.kill if thread.alive?
  end

  [mm_stdin, mm_stdout, mm_stderr].each { |io| io.close rescue nil }

  mm_wait_thr&.value rescue nil

  PWN::SDR::GQRX.disconnect_udp(udp_listener: udp_listener) if defined?(udp_listener) && udp_listener

  .stop if defined?() && 
end

.help ⇒ Object

Display Usage for this Module



245
246
247
248
249
250
251
252
253
 
# File 'lib/pwn/sdr/decoder/flex.rb', line 245

public_class_method def self.help
  puts "USAGE:
    #{self}.decode(
      freq_obj: 'required - freq_obj returned from PWN::SDR::GQRX.init_freq method'
    )

    #{self}.authors
  "
end